@dpunked I playtested Oath, but I've never played the final ruleset (we did all of our contributions at the beginning before covid started). It is complex though, and requires people to really sign on for that experience so I agree with that inclusion.
I've played a snot load of Terra Mystica and I've heard that Gaia Project is effectively "Space TM w/ a variable setup." I've also played a lot of FCM, the expansion really helps the game, if for nothing else than the new milestones. I would have nominated Indonesia over FCM, but that's purely personal.
Even if you exclude wargames though (so ASL, Here I Stand, etc which all have monster level rulebooks), the one omission I'm surprised about is that John Company 2nd didn't make it. That's like 45 pages but its doable. It's not like it's out of print or just unavailable either. Might not be able to walk into a generic hobby game store and pick it up, but that's a bending of the criteria IMHO (even if the article is intended to be a list of complex stuff that would be something you graduate to, which excludes High Frontier for example). Overall not a bad list.
PS: High Frontier should be a computer game for the rules enforcement standpoint and I'll die on that hill. Also, while the rules are only 1 sheet of paper, Southern Pacific from Winsome should be a computer game for the automated accounting alone...
@fathermackenzie since our group has an uneven distribution of game ownership, we bring things to the table and the first person to nominate a diverse set of N games (where N is the quantity of players) as a cohort of games starts the process. Then everyone gets to remove one game (the original selecting person doesn't because they defined the cohort) until you have just one title remaining.
That's effectively the "least bad" choice at the time, because people remove the title they least want to play and the remaining game is not the bottom choice. It also means you have to sort of read the audience for what they might go for (e.g. don't pick 5 train games for a mixed group where a disproportionate number don't like train games). Given enough time, everyone will get to define the cohort once.